Method for storing and playback of fixed videotexts

Abstract

In a method for storing and playback of a repertoire of fixed videotexts, in which the videotext is stored by characters in digital form in an electrical memory, the quantity of the data to be stored can be effectively reduced in that in addition to the characters, position characters are stored and that for recurring, identical character sequences of greater length, instead of the character sequence, a reference to the location of the already stored character sequence is stored. The playback of the thus compressed texts can take place without problems in real time, i.e., without noticeable delay.

We claim: 
     
       1. Method for storing and playback of a repertoire of fixed videotext for performing an operator control on a television screen, in which the videotext is stored by characters in digital form in an electrical memory, wherein for forming said videotext of one page position data are stored in a first memory, said position data indicating the position of a text sequence to be formed, addresses for forming said text sequence being stored in a second memory which refer to language independent phrases stored in a third memory and to language dependent phrases stored in a fourth memory, and a separate address is assigned to each of those parts of a text occuring often. 
     
     
       2. Method according to claim 1, wherein the repertoire of fixed videotexts is stored in the form of text sections and an assignment of the text sections belonging to a videotext is stored. 
     
     
       3. Method according to claim 1, wherein for a videotext, only assignments to those text portions that differ from a possible preceding videotext are stored. 
     
     
       4. Method according to claim 1, wherein the characters are stored according to a frequency-oriented bit-length-variable coding to decrease the bits to be stored. 
     
     
       5. Method according to claim 4, wherein a Huffman tree is produced for the bit-length-variable coding.